The invention relates to joint knee prostheses. More particularly, the invention is directed to tibial components of rotatable and non-rotatable knee joint prostheses that have a modular tibial bearing insert.
Joint replacement surgery is quite common and enables many individuals to function normally when otherwise it would not be possible to do so. Artificial joints usually comprise metallic, ceramic and/or plastic components that are fixed to existing bone.
Knee arthroplasty is a well known surgical procedure by which a diseased and/or damaged natural knee joint is replaced with a prosthetic knee joint. Typical knee prostheses include a femoral component, a patella component, a tibial tray or plateau, and a tibial bearing insert. The femoral component generally includes a pair of laterally spaced apart condylar portions, the distal surfaces of which articulate with complementary condylar elements formed in a tibial bearing insert.
The tibial tray is mounted within the tibia of a patient. Typically, the tibial bearing insert, which is usually made of ultra high molecular weight polyethylene (UHMWPE), is mounted upon the superior surface of the tibial plateau. The geometry of the tibial bearing insert varies depending upon the needs and joint condition of a patient. Some other tibial bearing inserts are designed to be used with joint prostheses that are implanted during procedures that retain the cruciate ligaments. Others are implanted after removal of the cruciate ligaments, and are thus structured to compensate for the loss of these ligaments. Yet other tibial bearing inserts are used with prostheses that provide enhanced stabilization to the knee joint. In addition to the geometry that may be assumed by a tibial bearing insert of a joint prosthesis, the tibial bearing insert may be designed so as to be fixed or rotatable with respect to the tibial plateau upon which it is mounted.
It is not normally possible for a surgeon to make a final determination in advance of surgery the type of knee prosthesis system that will best suit a patient. This decision is not made until the condition of the knee is assessed in the course of surgery.
As a result of the numerous candidate designs for knee joint prostheses, each of which may have a different geometry and varying degrees of constraint and thickness, numerous prosthesis components of differing designs may be used or trialed during a surgical procedure before the appropriate components are selected. Accordingly, a large inventory of parts is required during a joint replacement surgical procedure, thus adding to the cost of surgery. It would thus be advantageous to provide a joint prosthesis system that utilizes modular components to reduce the overall inventory count and to reduce the inventory carrying costs associated with joint replacement surgery.